TWI577073B - Composition for photoelectric conversion layer and photoelectric conversion element - Google Patents

Description

Composition for photoelectric conversion layer and photoelectric conversion element

The present invention relates to a composition for forming a photoelectric conversion layer, which constitutes a photoelectric conversion element such as a solar cell (particularly, a dye-sensitized solar cell), and an electrode (photoelectrode) using the composition and A photoelectric conversion element having the electrode.

As a green energy source with a small environmental load, solar cells are attracting attention and have actually been put into practical use. At present, a solar cell using a crystalline ruthenium has been widely used. However, since high-purity enthalpy is used, the power generation cost is high, and the conversion efficiency to weak light such as indoors is small.

In order to solve this problem, solar cells using organic materials for photoelectric conversion sites have been vigorously developed, and dye-sensitized solar cells are attracting attention. The dye-sensitized solar cell is developed by Graetzel et al., of the University of Technology, Lausanne, Switzerland. For example, Japanese Patent No. 2664194 (Patent Document 1) has a metal oxide semiconductor (such as titanium oxide) and a sensitizing dye used in photovoltaics. Important features of the transition site.

Further, in the conventional solar battery, there is a problem in that the power supply is stably supplied: only the period during which the light is irradiated is generated, and at night, the function as a battery is not exhibited, and the output is varied in accordance with the intensity of the light. In order to solve this problem, there will be a case where a solar cell is used together with a power storage device.

Also, in a dye-sensitized solar cell, an attempt has been made to combine the power storage function. For example, Japanese Patent No. 4475433 (Patent Document 2) discloses a rechargeable solar cell in which a cation exchange membrane is interposed and exists. The first electrolyte solution and the second electrolyte solution, the first electrolyte solution and the second electrolyte solution are separated from the outside air, the first electrolyte solution contains iodine and an iodine compound, and the second electrolyte solution contains a non-iodine compound, and the first electrolyte The constituent components of the solution are different from the constituent components of the second electrolyte solution, and a photoanode and a counter electrode are present in the first electrolyte solution, and a charge storage electrode is present in the second electrolyte solution, and the photoanode and the charge storage are The electrode system is separated by the above cation exchange membrane.

However, in the dye-sensitized solar cell of this document, in order to provide a storage function, it is necessary to use two types of electrolytes having different compositions, and it is necessary to create a very complicated unit structure by adding a new electrode. Further, since polypyrrole or the like is used for the positive electrode, the internal resistance is increased, and the output of the dye-sensitized solar cell is mainly reduced. In addition, since the output from the solar cell is different from the electrode used for the output (discharge) from the electric double layer capacitor, it is necessary to control by an external circuit, and it becomes a complicated circuit structure.

On the other hand, in the dye-sensitized solar cell, since the photoelectric conversion system occurs at the contact interface between the metal oxide semiconductor and the sensitizing dye, it is desirable to increase the surface area of the metal oxide semiconductor in order to improve the efficiency. Therefore, in the dye-sensitized solar cell, by using a nano-sized metal oxide semiconductor for the electrode, the effective area is enlarged with respect to the apparent area.

When the metal oxide nanoparticles are simply applied to the substrate, the impact is easily peeled off from the substrate, and the function as an electrode cannot be exhibited. Further, since the electric resistance between the particles is large, the obtained electric power cannot be efficiently extracted, and the conversion efficiency is lowered. Therefore, after the titanium oxide nanoparticles are coated, the above problems are solved by heat-treating at a high temperature (about 450 ° C) to melt-bond the titanium oxide particles.

However, in the above method, it is necessary to expose the substrate to a high temperature, and the substrate that can be used substantially is limited by an inorganic material such as glass, and it is not possible to produce a flexible dye-sensitized solar cell using a plastic substrate.

Moreover, since it is thermally decomposed during the sintering process, it is impossible to adsorb the dye to the metal oxide semiconductor before coating, and after the sintering process, the process of dye adsorption becomes necessary, including the sintering process, and the whole is complicated. Process is necessary and also the main cause of rising manufacturing costs.

Japanese Patent Laid-Open Publication No. 2005-251426 (Patent Document 3) discloses a method in which a dye is bonded to a method in which a dye can be bonded to a conductive substrate and a bonded dye is released. A metal oxide, a metal sulfide, a metal nitride, a metal cluster or an alloy thereof is immobilized on the substrate, and the amount of current generated by irradiating the light is measured, and the amount of current is measured from the amount of the current. The amount of pigment in the knot. Further, in this document, a method for immobilizing a dye to release a dye is described, and a method using a polymer electrolyte is preferred. In the examples, Nafion (Nafion (R), Aldrich Co., Ltd.) is described. , trade name: Nafion 117, average molecular weight 1000) suspended in 1ml of ethanol, will A 20.5% titanium oxide fine particle aqueous solution (manufactured by TAYCA Co., Ltd., trade name: TKS-203, particle size: about 6 nm) was added in an amount of 400 ml, and a titanium oxide-modified ITO electrode was prepared by using a titanium oxide Nafion sol dispersion obtained by uniform dispersion.

Prior technical literature Patent literature

Patent Document 1 Japanese Patent No. 2664194 (Application Patent Range)

Patent Document 2 Japanese Patent No. 4475433 (Application Patent Range, Examples)

Patent Document 3 Japanese Laid-Open Patent Publication No. 2005-251426 (Patent Application, Paragraph [0011] to [0012], and Examples)

Therefore, an object of the present invention is to provide an electrode (layered body) capable of forming a photoelectric conversion layer having a storage function, a photoelectric conversion layer formed using the composition, a method for producing the same, and a photovoltaic having the electrode Conversion component.

Another object of the present invention is to provide a composition capable of forming a photoelectric conversion layer having excellent photoelectric conversion characteristics without undergoing a sintering step, a laminate (electrode) of a photoelectric conversion layer formed by the composition, and A manufacturing method and a photoelectric conversion element including the laminate.

As a result of intensive studies to solve this problem, the present inventors have found that a large amount of an ionic polymer (for example, a strongly acidic ion exchange resin) is used for a semiconductor (for example, titanium oxide particles or the like) in a photoelectric conversion layer. Or) or a combination of a semiconductor and an ionic polymer (for example, a combination of an n-type semiconductor and an anionic polymer), and unexpectedly obtain a photoelectric device having a photoelectric conversion function and a storage function which are both desirable for the opposite function. Further, the conversion element (solar battery or the like) can form a photoelectric conversion layer having excellent photoelectric conversion characteristics even without sintering, and thus the present invention has been completed.

That is, the composition of the present invention (composition for a photoelectric conversion layer) is a composition for forming a photoelectric conversion layer, and contains a semiconductor and an ionic polymer. The photoelectric conversion layer formed of the composition may usually have a storage function. Further, in the composition, the ratio of the ionic polymer may be usually 0.05 parts by weight or more (for example, 0.05 to 100 parts by weight, preferably 0.1 to 10 parts by weight) based on 1 part by weight of the semiconductor.

In the composition of the present invention, the semiconductor may also be a metal oxide (e.g., titanium oxide). The size of the semiconductor can be a nanometer size, and the shape of the semiconductor can also be a particle shape. In a preferred semiconductor, titanium oxide nanoparticles are included.

In the composition of the present invention, typically, the combination of the semiconductor and the ionic polymer may be (i) a combination of an n-type semiconductor and an ionic polymer comprising an anionic polymer, or (ii) a p-type. A combination of a semiconductor and an ionic polymer comprising a cationic polymer. When using this combination to select a semiconductor and an ionic polymer (also, relative to semiconducting) When the amount of the ionic polymer is used in a large amount, a photoelectric conversion layer having an excellent storage function can be obtained.

In particular, the combination of the semiconductor and the ionic polymer may also be a combination (i). In this combination, a semiconductor (n-type semiconductor) containing titanium oxide particles or the like can be suitably used as the n-type semiconductor.

In the combination (i), the anionic polymer may, for example, be a strongly acidic ion exchange resin. Further, the pH of the anionic polymer at 25 ° C may also be less than 7.

In a representative composition of the present invention, the semiconductor comprises titanium oxide nanoparticles, and the ionic polymer is an ionic polymer having a pH of 3 or less containing a fluorine-containing resin having a sulfonic acid group, and is 1 part by weight relative to the semiconductor. The ratio of the ionic polymer is 0.2 to 1 part by weight of the composition or the like.

The composition of the present invention may further contain a pigment (for example, a ruthenium complex dye).

In the present invention, a laminate (electrode) includes a conductive substrate and a photoelectric conversion layer laminated on the substrate, and the photoelectric conversion layer also includes a laminate formed using the composition. For example, the conductive substrate may be a plastic substrate on which a conductor layer (or a conductive layer) is formed. Further, in the laminate, for example, the thickness of the photoelectric conversion layer may be about 0.1 to 100 μm.

In the present invention, a method of producing the laminate by applying the composition onto a conductive substrate is also included. In this method, the laminate can be produced usually after sintering without causing the semiconductor (or the composition) to be sintered (or not subjected to a sintering step).

In the present invention, a photoelectric conversion element including the laminate (electrode) is also contained. The photoelectric conversion element usually has a counter electrode. In a typical solar-electric conversion element, a solar cell including the laminate as an electrode includes, for example, a dye-sensitized solar cell having the following structure: a laminate including a photoelectric conversion layer containing a dye as an electrode; The electrode is disposed; and the electrolyte layer is interposed between the electrodes and has been sealed. In the photoelectric conversion element (or dye-sensitized solar cell), the counter electrode may be a counter electrode (electrode) particularly having a porous layer (particularly a porous catalyst layer).

As described above, the composition of the present invention can be used as a composition for forming a photoelectric conversion layer having a storage function. Therefore, in the present invention, a method of imparting a storage function to the photoelectric conversion layer is also included. In the method, the photoelectric conversion layer containing the semiconductor may be ion-implanted to impart a storage function to the photoelectric conversion layer (the photoelectric conversion layer containing the semiconductor) (or to manufacture a photoelectric conversion layer having a storage function, or to improve or improve photoelectric conversion). The method of storage function of the layer). Further, in this method, the type or ratio of the semiconductor or the ionic polymer contains a preferred form, and is the same as the composition. For example, in the method, the ratio (content ratio) of the ionic polymer may be the same ratio as described above [that is, 0.05 parts by weight or more (for example, 0.05 to 100 parts by weight) based on 1 part by weight of the semiconductor. )].

In the composition of the present invention, a photoelectric conversion layer having a storage function can be formed. Further, a photoelectric conversion layer having superior photoelectric conversion characteristics can be formed without undergoing a sintering step. Therefore, in the present invention, The plastic substrate can also be used as a substrate without exposing the substrate to high temperatures. When the plastic substrate is used, a flexible electrode or a photoelectric conversion element can be obtained. Further, since the sintering step is not subjected to the sintering step, the process of the photoelectric conversion layer can be simplified, and in particular, in the case of forming the dye-sensitized photoelectric conversion layer, since the dye can be attached or adsorbed to the semiconductor in advance, the effect of simplifying the process is excellent. .

Fig. 1 is a graph showing the output characteristics of the dye-sensitized solar cell obtained in the examples.

Fig. 2 is a graph showing changes in open voltage after shading of the dye-sensitized solar cell obtained in the examples.

[Formation of the Invention] [Composition for photoelectric conversion layer]

The composition of the present invention contains at least a semiconductor and an ionic polymer. As will be described later, this composition is particularly useful as a composition for forming a photoelectric conversion layer (or a photoelectric conversion layer constituting an electrode) constituting an electrode.

(semiconductor)

The semiconductor can be roughly classified into an inorganic semiconductor or an organic semiconductor, and in the present invention, an inorganic semiconductor can be suitably used. The inorganic semiconductor may be appropriately selected according to the use, and may be, for example, a metal monomer or a metal compound (metal oxide, metal sulfide, metal nitride, or the like).

Examples of the metal constituting the inorganic semiconductor include metals of Group 2 of the periodic table (for example, calcium, barium, etc.), metals of Group 3 of the periodic table (for example, ruthenium, osmium, iridium, etc.), and metals of Group 4 of the periodic table. (eg, titanium, zirconium, hafnium, etc.), Group 5 metals of the periodic table (eg, vanadium, niobium, tantalum, etc.), Group 6 metals of the periodic table (eg, chromium, molybdenum, tungsten, etc.), Group 7 of the periodic table Metal (for example, manganese, etc.), Group 8 metal of the periodic table (for example, iron, etc.), Group 9 metal of the periodic table (for example, cobalt, etc.), Group 10 metal of the periodic table (for example, nickel, etc.), periodic table Group 11 metals (eg, copper, etc.), Group 12 metals of the periodic table (eg, zinc, cadmium, etc.), Group 13 metals of the periodic table (eg, aluminum, gallium, indium, antimony, etc.), Group 14 metals of the periodic table (for example, antimony, tin, etc.), Group 15 metals of the periodic table (for example, arsenic, antimony, antimony, etc.), Group 16 metals of the periodic table (for example, antimony, etc.), and the like.

The semiconductor may be a compound containing the metals alone or a compound containing a plurality of combinations. For example, the semiconductor may be an alloy, and the metal oxide may also be a composite oxide. Further, the semiconductor may contain a combination of the above metal and another metal (alkali metal or the like).

Specific examples of the semiconductor include metal oxides (for example, transition metal oxides [for example, metal oxides of Group 3 of the periodic table (cerium oxide, cerium oxide, etc.), metal oxides of Group 4 of the periodic table (oxidation) Titanium, zirconia, calcium titanate, barium titanate, etc.), Group 5 metal oxides of the periodic table (vanadium oxide, antimony oxide, antimony oxide (bismuth pentoxide, etc.), etc.), Group 6 metal oxides of the periodic table (Chromium oxide, tungsten oxide, etc.), Group 7 metal oxides of the periodic table (manganese oxide, etc.), Group 8 metal oxides of the periodic table (iron oxide, cerium oxide, etc.), Group 9 metal oxides of the periodic table (oxidation) Cobalt, cerium oxide, composite oxide of cobalt and sodium, etc., metal oxide of Group 10 of the periodic table (nickel oxide, etc.), metal oxide of Group 11 of the periodic table (copper oxide, etc.), metal oxidation of Group 12 of the periodic table (zinc oxide, etc.), etc., typical metal oxides [for example, metal oxides of the second group of the periodic table (such as cerium oxide), metal oxides of Group 13 of the periodic table (gallium oxide, indium oxide, etc.), periodic table Group 14 metal oxides (yttria, tin oxide, etc.), Group 15 metal oxides of the periodic table (yttria, etc.), etc. a composite oxide containing a plurality of such metals [for example, a composite oxide of a metal of Group 11 of the periodic table and a transition metal (a transition metal other than a metal of Group 11 of the periodic table) (for example, copper of CuYO ₂ or the like) a composite oxide of a Group 3 metal), a composite oxide of a Group 11 metal of a periodic table and a typical metal (for example, a composite oxide of copper such as CuAlO ₂ , CuGaO ₂ , CuInO _{2 ,} etc. and a Group 13 metal of the periodic table; SrCu _{2 ;} a composite oxide of O ₂ or the like and a metal of a Group 2 metal of the periodic table; a composite oxide of AgInO ₂ or the like and a metal of a Group 13 metal of the periodic table, etc.), the plurality of metals, and a periodic table other than oxygen Oxides of Group 16 elements [eg, complex oxysulfides of Group 11 metals of the Periodic Table and transition metals (transition metals other than Group 11 metals of the Periodic Table) (eg, copper such as LaCuOS and metals of Group 3 of the periodic table) Complex oxysulfide), composite oxylyzide of Group 11 metal of the periodic table and transition metal (transition metal other than Group 11 metal of the periodic table) (for example, composite oxygen of copper such as LaCuOSe and metal of Group 3 of the periodic table) Selenide), etc.], metal nitride (tantalum nitride, etc.) ), metal phosphide (InP, etc.), metal sulfide {eg, CdS, copper sulfide (CuS, Cu ₂ S), composite sulfide [eg, composite sulfide of Group 11 metal and typical metal of the periodic table (for example, CuGaS ₂ , CuInS ₂ and other composite sulfides of metals of the 13th group of the periodic table), metal selenides (CdSe, ZnSe, etc.), metal halides (CuCl, CuBr, etc.), metals of Group 13 of the periodic table - a metal compound (or alloy) of a Group 15 metal compound (GaAs, InSb, etc.), a Group 12 metal of a periodic table, a Group 16 metal compound (CdTe, etc.), or the like; a metal monomer (for example, palladium, platinum, silver, Gold, 矽, 锗) and so on.

Also, the semiconductor may be a semiconductor doped with other elements.

The semiconductor can be an n-type semiconductor or a p-type semiconductor. In the present invention, among the ionic polymers described later, an anionic polymer for an n-type semiconductor and a cationic polymer for a p-type semiconductor may be appropriately combined. By this combination, a photoelectric conversion layer having an efficient storage function can be formed.

Among the semiconductors (especially inorganic semiconductors) exemplified above, examples of the n-type semiconductors include, for example, metal oxides of Group 4 of the periodic table (such as titanium oxide) and metal oxides of Group 5 of the periodic table (oxidation).铌, yttrium oxide, etc.), Group 12 metal oxides (zinc oxide, etc.) of the periodic table, etc., Group 13 metal oxides of the periodic table (gallium oxide, indium oxide, etc.), Group 14 metal oxides of the periodic table (oxidation) Tin, etc.).

In addition, examples of the p-type semiconductor include a metal oxide of a Group 6 of the periodic table (such as chromium oxide), a metal oxide of Group 7 of the periodic table (manganese oxide or the like), and oxidation of a metal of Group 8 of the periodic table. (iron oxide, etc.), metal oxide of Group 9 of the periodic table (cobalt oxide, antimony oxide, etc.), metal oxide of Group 10 of the periodic table (nickel oxide, etc.), metal oxide of Group 11 of the periodic table (copper oxide, etc.) ), Group 15 metal of the periodic table (antimony oxide, etc. ₎ , composite oxide of Group 11 metal and transition metal or typical metal of the periodic table (for example, CuYO ₂ , CuAlO ₂ , CuGaO ₂ , CuInO ₂ , SrCu ₂ O ₂ , AgInO _2, etc., composite oxysulfide of Group 11 metal and transition metal of the periodic table (for example, LaCuOS, etc.), composite oxyselele of metal of Group 11 and transition metal of the periodic table (for example, LaCuOSe, etc.), cycle A composite sulfide of a Group 11 metal and a typical metal (for example, CuGaS ₂ , CuInS _{2 ,} etc.) or the like.

These semiconductors may be used alone or in combination of two or more.

Among these, a preferred semiconductor contains a metal oxide, and particularly preferably a transparent metal oxide (metal oxide having transparency). Examples of the metal oxide include titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), and copper-aluminum. Oxide (CuAlO ₂ ), yttrium oxide (IrO), nickel oxide (NiO), dopants of such metal oxidation, and the like.

Further, among semiconductors, an n-type semiconductor can be suitably used from the viewpoint of electron conductivity and the like. In particular, in the present invention, an n-type metal oxide semiconductor such as titanium oxide (TiO ₂ ) is suitably used.

The crystal form (crystalline form) of titanium oxide may be any of rutile type, anatase type (anatase type), and plate titanium type (brookite type). In the present invention, rutile-type or anatase-type titanium oxide can be suitably used, and an anatase-type titanium oxide is particularly preferable. On the other hand, since the rutile-type titanium oxide is easily oriented and the contact area between the titanium oxides can be further enlarged, it is also suitable for use in terms of electrical conductivity and durability.

The shape of the semiconductor (for example, a metal oxide such as titanium oxide) is not particularly limited, and may be a particulate form, a fibrous form (or a needle shape, a rod shape), a plate shape or the like. The preferred shape is a particle shape or a needle shape, and particularly preferably a particulate semiconductor (semiconductor particle).

The average particle diameter (average primary particle diameter) of the semiconductor particles can range from about 1 to 1000 nm (for example, from 1 to 700 nm), and can be usually a nanometer size, for example, from 1 to 500 nm (for example, from 2 to 400 nm). It may be 3 to 300 nm (for example, 4 to 200 nm), further preferably 5 to 100 nm (for example, 6 to 70 nm), and particularly preferably 50 nm or less [for example, 1 to 50 nm (for example, 2 to 40 nm), It is preferably 3 to 30 nm (for example, 4 to 25 nm), further preferably 5 to 20 nm (for example, 6 to 15 nm), and usually 10 to 50 nm].

Further, in the acicular (or fibrous) semiconductor, for example, the average fiber diameter may be from 1 to 300 nm, preferably from 10 to 200 nm, and more preferably from 50 to 100 nm. Further, in the acicular semiconductor, the average fiber length may be from 10 to 2,000 nm, preferably from 50 to 1,000 nm, and further preferably from about 100 to 500 nm. In the acicular semiconductor, for example, the aspect ratio may be from 2 to 200, preferably from 5 to 100, and further preferably from about 20 to about 40.

The specific surface area of the semiconductor (for example, a fibrous or particulate semiconductor) depends on the shape and the like, and may be, for example, 1 to 600 m ² /g, preferably 2 to 500 m ² /g, and more preferably 3 to 400m ² /g or so.

In particular, for example, the specific surface area of the semiconductor particles may be from 5 to 600m ² / g (e.g., 7 to 550m ² / g), may be preferably 10 to 500m ² / g (e.g., 15 to 450m ² / g), more than It may be 20 to 400 m ² /g (for example, 30 to 350 m ² /g), particularly preferably 50 m ² /g or more (for example, 50 to 500 m ² /g, preferably 70 to 450 m ² /g, further) It is preferably 100 to 400 m ² /g, particularly preferably 150 to 350 m ² /g (for example, 200 to 350 m ² /g)].

Further, the fibrous or needle-shaped semiconductor may have a specific surface area of from 1 to 100 m ² /g, preferably from 2 to 70 m ² /g, further preferably from 3 to 50 m ² /g (for example, from 4 to 30 m) ² / g) or so.

Further, a semiconductor (such as titanium oxide) can be used as a dispersion (such as an aqueous dispersion) and can be mixed with an ionic polymer (and a dye described later). Further, the semiconductor can be commercially available, and those synthesized by a conventional method can also be used. For example, a dispersion of titanium oxide can be obtained by the method described in Japanese Patent No. 4522886 or the like.

(ionic polymer)

The present invention is characterized by a combination of a semiconductor and an ionic polymer (composite). By this combination, a photoelectric conversion layer (a so-called electric double layer or a photoelectric conversion layer functioning as a capacitor) having both a photoelectric conversion function and a storage function can be formed. Further, the ionic polymer functions as an adhesive or can form a photoelectric conversion layer having excellent photoelectric conversion characteristics even without sintering a semiconductor (such as titanium oxide nanoparticles). Although this reason has not yet been determined, it is considered that the combination of an ionic polymer and a semiconductor [in particular, a semiconductor particle of a nanometer size (semiconductor nanoparticle)] can improve the dispersion stability of the semiconductor and can effectively exhibit the semiconductor. The ionic polymer itself also functions as an electrolyte (solid electrolyte) for transporting electric charges generated in accordance with photoelectric conversion, or the like, depending on the type of the ionic polymer.

When the ionic polymer (ionic polymer) is an ionic (electrolytic) polymer (that is, a polymer electrolyte), it may be an anionic polymer, a cationic polymer, or an amphoteric polymer ( Any of a polymer having a carboxyl group and an amine group, and the like.

In the present invention, representatively, an ionic polymer may be selected depending on the type of semiconductor. That is, (i) when the semiconductor is an n-type semiconductor, an ionic polymer containing an anionic polymer may be selected, and (ii) when the semiconductor is a p-type semiconductor, an ionic polymer containing a cationic polymer may also be selected. . The combination of the semiconductor and the ionic polymer, although not yet determined, can provide a superior charge storage function to the photoelectric conversion layer with high efficiency.

In particular, in the present invention, it is generally suitable to use an anionic polymer or a cationic polymer, and it is particularly suitable to use an anionic polymer (in particular, an n-type semiconductor and an ionic polymer containing an anionic polymer may also be selected. The combination). The anionic polymer or the cationic polymer is easily bonded to the surface of a semiconductor (titanium oxide or the like) by bonding (chemical bonding, hydrogen bonding, or the like), or is suitable for functioning as an adhesive. In particular, the ionic polymer may also be an ion exchange resin (or ion exchange or solid polymer electrolyte).

The anionic polymer is usually a polymer having an acid group [carboxy group, sulfonic acid group, etc.]. The anionic polymer may have a single acid group (or an acidic group) or a combination of two or more. Also, the acid group may neutralize part or all of it.

Typical examples of the anionic polymer [or a cationic exchange resin (cationic ion exchange resin, acid type ion exchange resin)] include a strongly acidic cation exchange resin and a weakly acidic cation exchange resin {for example, having a carboxyl group. An ion exchange resin [for example, a (meth)acrylic polymer (for example, poly(meth)acrylic acid; methacrylic acid-divinylbenzene copolymer, acrylic acid-divinylbenzene copolymer, etc.) a copolymer of (meth)acrylic acid and another copolymerizable monomer (crosslinkable monomer, etc.), a fluorine-containing resin having a carboxyl group (perfluorocarboxylic acid resin), and the like].

Among them, among the preferred anionic polymers, a strongly acidic cation exchange resin is contained. As the strongly acidic cation exchange resin, for example, a fluorine-containing resin having a sulfonic acid group {for example, a copolymer of fluoroolefin and a sulfonic acid fluoroalkyl-fluorovinyl ether [for example, tetrafluoroethylene-[2- a fluorosulfonic acid resin (especially, a perfluorosulfonic acid resin) such as a (2-sulfonic acid tetrafluoroethoxy) hexafluoropropoxy]trifluoroethylene copolymer (for example, a graft copolymer) or the like] A styrene-based resin having a sulfonic acid group (for example, a telluride of a polystyrenesulfonic acid or a crosslinked styrene-based polymer (for example, a telluride such as a styrene-divinylbenzene copolymer) or the like].

Further, a fluorine-containing resin having a sulfonic acid group is available from DuPont Co., Ltd. under the trade name "Nafion" series.

The anionic polymer may be any of acidic, neutral, and basic. In particular, in the present invention, an anionic polymer having a small pH can also be suitably used. When the pH is small, in combination with a semiconductor (especially an n-type semiconductor), since an electric double layer may be easily formed in an electrolytic solution, it is easy to obtain a sufficient electric storage function. Although the reason has not yet been determined, it is considered that the reason why the charge is easily retained on the semiconductor due to the abundant protons is also a cause. The pH of the anionic polymer (for example, strongly acidic cation exchange resin) or the ionic polymer containing an anionic polymer (25 ° C) can be selected from the range of 10 or less (for example, 0.1 to 8), for example, Less than 7 (for example, 0.15 to 6.5), preferably 6 or less (for example, 0.2 to 5), further preferably 4 or less (for example, 0.3 to 3), particularly preferably 2 or less (for example, 0.5 to 1.5), Usually also 3 or less (example For example, 1 to 3). Also, the pH may be a value in an aqueous solution or an aqueous dispersion of an ionic polymer (or a value in a solvent containing water). In other words, at 25 ° C, the pH may be a value (pH) of a solution (aqueous solution, etc.) or a dispersion (aqueous dispersion, etc.) when the ionic polymer is dissolved or dispersed in water or an aqueous solvent. .

Further, the pH can be adjusted by a conventional method (for example, a method of neutralizing an acid group with an appropriate base). Further, in the case of neutralizing the acid group, the relative ion is not particularly limited in the neutralized acid group, and may be, for example, an alkali metal (for example, sodium, potassium, or the like).

Further, in the case where the anionic polymer is used as the ionic polymer, the ionic polymer may be formed only by the anionic polymer, and the anionic polymer and other ionic polymers (for example, an amphoteric polymer or the like may be combined. ). In this case, the ratio of the anionic polymer to the entire ionic polymer is, for example, 30% by weight or more (for example, 40 to 99% by weight), preferably 50% by weight or more (for example, 60 to 98% by weight), and further. It is preferably 70% by weight or more (for example, 80 to 97% by weight).

The cationic polymer is usually a polymer having a basic group (basic group). Examples of the base group include an amine group [for example, an amine group, a substituted amine group (for example, a mono- or dialkylamino group such as a dimethylamino group), or the like, and the first or second stage or A third amino group, an imido group (-NH, -N<), a fourth-order ammonium base (for example, a trialkylammonium base such as a trimethylammonium base), or the like. The cationic polymer may have two or more of these basic groups alone or in combination. Further, the base group may also neutralize a part or all of it.

Specific examples of the cationic polymer [or anion exchange resin (anionic ion exchange resin, base type ion exchange resin) include, for example, an amine polymer {for example, an allylamine polymer [polyene] Allylamine-based monomer such as propylamine, allylamine-dimethylallylamine copolymer, diallylamine-sulphur dioxide copolymer (for example, allylamine, diallylamine) a copolymer or a copolymer of diallylalkylamine (diallylmethylamine, diallylethylamine, etc.) or the like (not only a copolymer of a plurality of allylamine monomers but also A copolymer of an allylamine-based monomer and a copolymerizable monomer, which is the same as in the following description), a vinylamine-based polymer (for example, a vinylamine-based monomer or copolymerization of a polyvinylamine or the like). (meth)acrylic polymer having an amine group [for example, aminoalkyl (meth) acrylate (for example, (meth)acrylic acid-N,N-dimethylaminoethyl ester, (A) (meth)acrylic acid-N,N-dimethylaminopropyl (meth)acrylic acid-N-mono or dialkylamino C _1-4 alkyl ester), aminoalkyl (meth) acrylate Amine , N, N- dimethylaminoethyl (meth) acrylate, etc. Amides N- mono- or dialkylamino C _1-4 alkyl (meth) acrylate, acyl amine), etc. having amine alone (meth)acrylic monomer or copolymer, etc.], heterocyclic amine polymer [for example, an imidazole polymer (for example, polyvinylimidazole) or a pyridine polymer (for example, polyvinylpyridine) , pyrrolidone-based polymer (for example, polyvinylpyrrolidone), etc., amine-modified epoxy resin, amine-modified decane resin, etc., imine-based polymer [for example, polyalkyleneimine (e.g., a single imine monomer or copolymer such as polyethylenimine or the like), a polymer containing a fourth-order ammonium base, or the like.

In the polymer containing a fourth-order ammonium base, the salt is not particularly limited, for example, a halide salt (for example, chloride, bromide, Iodide or the like), a carboxylate (for example, an alkanoate such as acetate), a sulfonate or the like.

Examples of the polymer containing a fourth-order ammonium base include a polymer in which the amine group or the imine group of the amine-based polymer or the imine polymer exemplified above is subjected to the fourth-stage ammonium grouping. {For example, N,N,N-trialkyl-N-(methyl)propenyloxyalkylammonium salt alone [eg, trimethyl-2-(methyl)propene oxiranyl ammonium chloride, Tri-C _1-10 alkyl (meth) propylene oxirane C _2-4 alkyl group such as N,N-dimethyl-N-ethyl-2-(methyl) propylene oxiranyl ammonium chloride An ammonium salt] or a copolymer}, and also a vinyl aralkyl ammonium salt-based polymer {for example, a vinyl aralkyl ammonium salt alone [for example, N, N, N-trialkyl-N-(ethylene) Alkylalkyl)ammonium salt (for example, trimethyl-p-vinylbenzylammonium chloride, N,N-dimethyl-N-ethyl-p-vinylbenzylammonium chloride, N,N 3-C _1-10 alkyl group such as diethyl-N-methyl-N-2-(4-vinylphenyl)ethylammonium chloride (vinyl-C _6-10 aryl C _1-4 Alkyl) ammonium salt), N,N-dialkyl-N-aralkyl-N-(vinyl aralkyl) ammonium salt (eg, N,N-dimethyl-N-benzyl-p- N,N-di-C _1-10 alkyl-NC _6-10 aryl C _1-4 alkyl-N-(vinyl-C) such as vinyl benzyl ammonium chloride _6-10 aryl C _1-4 alkyl) ammonium salt)] or copolymer, etc.}, cationized cellulose [for example, a cellulose derivative containing a hydroxyl group (for example, a hydroxyl group C _{2- of} hydroxyethyl cellulose or the like) _4- alkyl cellulose) and an epoxy compound having a fourth-order ammonium salt (for example, a trialkylammonium base or the like) (for example, N, N, N-trialkyl-N-epoxypropyl ammonium salt) The reactant] is a polymer obtained by introducing a fourth-order ammonium base into a styrene-divinylbenzene copolymer.

Further, cationic cellulose (cationized cellulose) can be obtained from Daicel Co., Ltd. under the trade name "JELLNER". The polyallylamine can be obtained from the product name "PAA" series of Nittobo Medical Co., Ltd., and the amine-modified siloxane resin can be obtained from the trade name "KF" series of Shin-Etsu Chemical Co., Ltd.

A preferred cationic polymer is a cationic polymer (anionic exchange resin) having a strong base property such as a polymer of a fourth-order ammonium base.

The cationic polymer may be any of acidic, neutral, and basic. In particular, in the present invention, in combination with a p-type semiconductor, a cationic polymer having a relatively high pH can also be suitably used. The pH (25 ° C) of the ionic polymer containing the cationic polymer (for example, a strongly basic anion exchange resin) or a cationic polymer can be selected from the range of 5 or more (for example, 6 to 14), for example, 7 or more (for example, 7.5 to 14), preferably 8 or more (for example, 8.5 to 14), further preferably 9 or more (for example, 9.5 to 13.5), and particularly preferably 10 or more (for example, 10.5 to 13). Further, the pH may be a value in an aqueous solution or an aqueous dispersion of an ionic polymer (or a value in an aqueous solvent). In other words, the pH is a value (pH) of a solution (aqueous solution or the like) or a dispersion (aqueous dispersion or the like) when the ionic polymer is dissolved or dispersed in water or an aqueous solvent at 25 ° C. Further, the pH can be adjusted by a conventional method (for example, a method of neutralizing a base group with an appropriate acid group).

Further, in the case where the cationic polymer is used as the ionic polymer, the ionic polymer may be formed only by the cationic polymer, or the cationic polymer and other ionic polymers (for example, an amphoteric polymer) may be combined. . In this case, for example, the ratio of the cationic polymer to the entire ionic polymer may be 30% by weight or more (for example, 40) To 99% by weight, preferably 50% by weight or more (for example, 60 to 98% by weight), further preferably 70% by weight or more (for example, 80 to 97% by weight).

The ionic polymer (an anionic polymer, a cationic polymer, etc.) may also have a crosslinked structure (for example, the exemplified (meth)acrylic acid-divinylbenzene copolymer or a styrene polymer telluride) Etc.), or may not have a crosslinked structure. In the present invention, it is particularly preferable to use an ionic polymer which does not have a crosslinked structure (or a very low degree of crosslinking).

In the ionic polymer (ion exchange resin), the ion exchange capacity may be from 0.1 to 5.0 meq/g (for example, from 0.15 to 4.0 meq/g), preferably from 0.2 to 3.0 meq/g (for example, from 0.3 to 2.0). Further preferably, the meq/g) may be from 0.4 to 1.5 meq/g, and particularly preferably from about 0.5 to 1.0 meq/g.

Further, the molecular weight of the ionic polymer is not particularly limited as long as it is in a range in which the solvent can be dissolved or dispersed.

The ionic polymer may be used alone or in combination of two or more.

The ratio of the ionic polymer can be selected from the range of 0.05 parts by weight or more (for example, 0.07 to 100 parts by weight) with respect to 1 part by weight of the semiconductor, and for example, may be 0.1 part by weight or more (for example, 0.1 to 50 parts by weight) It may preferably be 0.15 parts by weight or more (for example, 0.15 to 30 parts by weight), further preferably 0.2 parts by weight or more (for example, 0.2 to 20 parts by weight), and usually 0.1 to 10 parts by weight [for example, 0.1 to 8 parts by weight (for example, 0.1 to 7 parts by weight), preferably 0.15 to 5 parts by weight (for example, 0.15 to 3 parts by weight), further preferably 0.2 to 2 parts by weight (for example, 0.2 to 1 part by weight) Parts by weight)]. By as above The ratio of the semiconductor to the ionic polymer (further, the combination of the semiconductor and the ionic polymer is selected as described above) can efficiently obtain a photoelectric conversion layer having a storage function.

(pigment)

The composition of the present invention may further contain a pigment. By containing a dye, it is possible to efficiently form a dye-sensitized photoelectric conversion layer or a dye-sensitized photoelectric conversion element (such as a dye-sensitized solar cell).

The dye (dye, pigment) is not particularly limited as long as it exhibits a function as a sensitizer (sensitizing dye or photosensitizing dye) (or a component exhibiting a sensitizing effect), and for example, An organic dye or an inorganic dye (for example, a carbon pigment, a chromate pigment, a cadmium pigment, a ferrocyanide pigment, a metal oxide pigment, a citrate pigment, a phosphate pigment, or the like) is used. The pigments may be used alone or in combination of two or more.

As the organic dye (organic dye or organic pigment), for example, a ruthenium complex dye {for example, a ruthenium dipyridine complex [for example, cis-bis(isocyanato) bis (2, 2'-) can be mentioned. Bipyridine-4,4'-dicarboxyl) ruthenium (II) bistetrabutylammonium (alias: N719), cis-bis(isocyanato) (2,2'-dipyridine-4,4'- Dicarboxyl)(2,2'-bipyridine-4,4'-diindenyl)ruthenium(II), cis-bis(isocyanato)bis(2,2'-bipyridine-4,4' -dicarboxylated) ruthenium (II), cis-bis(cyano)(2,2'-bipyridine-4,4'-dicarboxylate) ruthenium (II), tris(2,2'-bipyridine- 4,4'-dicarboxylated) ruthenium (II) chloride, etc.], hydrazine-linked tripyridine complex [for example, tris(isocyanato) ruthenium (II)-2, 2':6', a pyridine-based complex of 2"-bitripyridine-4,4',4"-tricarboxylic acid tri(tetrabutyl)ammonium salt or the like], a ruthenium complex dye, or a porphyrin dye ( Magnesium porphyrin, zinc porphyrin, etc.) A chlorophyll-based pigment (such as chlorophyllin), a xanthone-based pigment (such as rhodamine B, erythromycin, etc.), an anthocyanin-based pigment (anthocyanin, quinocyanin, cryptocyanidin, etc.) ), anthraquinone-based pigment, azo-based pigment, anthraquinone-based pigment, anthrone-based pigment, coumarin-based pigment, anthraquinone-based pigment, anthraquinone-based pigment, squaric acid-based pigment, azomethine-based pigment, quinoline A yellow pigment, a quinophthalone dye, an isoindole dye, a nitroso dye, a pyrrolopyrrole dye, a base dye (methylene blue, etc.), or the like.

Among these pigments, an organic dye is preferred, and among them, a ruthenium complex dye is preferred. Further, a dye having a functional group such as a carboxyl group, an ester group or a sulfonic acid group as a ligand (for example, an anthracene dye having a carboxyl group such as N719) is also preferable. The dye having such a ligand is suitable because it is easily bonded to a semiconductor surface such as titanium oxide and is difficult to be detached.

Further, the dye is usually contained in the photoelectric conversion layer (photoelectric conversion element) in a state of being attached to (or being fixed to) a semiconductor (or a semiconductor surface). Examples of the form of adhesion (or immobilization) include adsorption (physical adsorption), chemical bonding, and the like. Therefore, the coloring matter is also suitable for selecting a pigment which is easy to adhere to a semiconductor.

The ratio of the pigment (adhesion or adsorption ratio) is not particularly limited, and is, for example, related to a semiconductor or an ionic polymer, and may be selected as a range of the following formula.

0<(I _A ×I _S +D _A ×D _S )/S _S 1

(In the formula, I _A represents the number of ionic groups in the ionic polymer, I _S represents the occupied area per ionic group, D _A represents the number of pigments (pigment molecules), and D _S represents The area occupied by each pigment and the S _S system represent the surface area of the semiconductor.)

In the above formula, the total number of I _A- based ionic groups, for example, the ion exchange capacity (meq/g) of the ionic polymer multiplied by the weight of the ionic polymer (g) and the Avogadro number (Avogadro number) It can be found, usually I _A × I _S <S _S . I _S, D _S is an area occupied by each ionic group of (m ^2), an area occupied by one molecule of dye (m ^2), can be used when the value of the largest area that the projection of the way.

With respect to 1 part by weight of the semiconductor, for example, the specific pigment ratio may be 0.001 to 1 part by weight (for example, 0.003 to 0.7 part by weight), preferably 0.005 to 0.5 part by weight (for example, 0.007 to 0.3 part by weight). Further, it is further preferably from about 0.01 to 0.2 parts by weight (for example, from 0.02 to 0.1 parts by weight).

The composition of the present invention may also be a composition containing a solvent (coating composition). The solvent is not particularly limited, and is an organic solvent (for example, an alcohol solvent (for example, an alkanol such as methanol, ethanol, isopropanol or butanol) or an aromatic solvent (for example, toluene or xylene). An aromatic hydrocarbon), an ester solvent (for example, ethyl acetate such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether monoacetate) or a ketone solvent (for example, a chain ketone such as acetone) a cyclic ketone such as cyclohexanone or an ether solvent (for example, a chain ether such as propylene glycol monomethyl ether or diethylene glycol dimethyl ether; a cyclic ether such as an alkane or a tetrahydrofuran), a halogen solvent (for example, a halogenated product such as dichloromethane or chloroform), a nitrile solvent (for example, acetonitrile or benzonitrile), or a nitro solvent (for example, Nitrobenzene, etc.), water, etc. The solvent may be used alone or in combination of two or more.

In the composition containing a solvent, the ratio of the solid matter (or the nonvolatile component) is a coating method at the time of forming the photoelectric conversion layer, etc. Suitably, for example, it may be 0.1 to 90% by weight (for example, 0.5 to 70% by weight), preferably 1 to 50% by weight (for example, 5 to 40% by weight), and further preferably 10 to 30% by weight. About weight%. In the present invention, since the ratio of the ionic polymer can be further increased, even if the solid content containing the semiconductor is high, the dispersion stability of the semiconductor can be sufficiently ensured.

Further, the pH of the composition containing the solvent is not particularly limited, and as described above, an appropriate range may be selected depending on the type of the ionic polymer or the combination with the ionic polymer of the semiconductor. For example, in the case where an anionic polymer is used to constitute the ionic polymer, the pH (25 ° C) of the composition containing the solvent can be selected from the range of 10 or less (for example, 0.1 to 8), for example, may be less than 7 (for example, 0.15 to 6.5), preferably 6 or less (for example, 0.2 to 5), further preferably 4 or less (for example, 0.3 to 3), and particularly preferably 2 or less (for example, 0.5 to 1.5), usually It is 3 or less (for example, 1 to 3).

Further, in the case where the cationic polymer is used as the ionic polymer, the pH of the composition containing the solvent (25 ° C) can be selected from the range of 5 or more (for example, 6 to 14), and for example, it can be 7 or more (for example, 7.5 to 14), preferably 8 or more (for example, 8.5 to 14), further preferably 9 or more (for example, 9.5 to 13.5), and particularly preferably 10 or more (for example, 10.5 to 13).

The composition of the present invention can be obtained by mixing the respective components (semiconductor, ionic polymer, optional dye, etc.). For example, the solvent-containing composition may be prepared by mixing the components in a solvent, or may be prepared by mixing (or dispersing) the components (for example, a semiconductor and an ionic polymer) in a solvent. . Also, as above In addition, a semiconductor such as titanium oxide may be mixed with an ionic polymer (and a dye) in a form of a dispersion in which it is dispersed in a solvent in advance. Further, as described above, when the pH of the composition is adjusted, the adjustment of the pH can be carried out at an appropriate stage, for example, by adjusting the pH in the dispersion of the semiconductor in such a manner as to be in the above range, and the ionic polymerization can be carried out. The substance (and the pigment) may be mixed, and the pH of the composition may be adjusted in a mixed system of a semiconductor (or a dispersion thereof) and an ionic polymer (and a pigment).

Further, the dye may be mixed with a semiconductor or an ionic polymer in advance, and the dye may be applied (adhered) to a coating film formed by applying a composition containing a semiconductor and an ionic polymer to a substrate. In the present invention, as described later, since it is not necessary to sinter (calcinate) the semiconductor, it is possible to mix with the semiconductor and the ionic polymer in advance.

The composition of the present invention is useful as a composition for forming a photoelectric conversion layer (or a photoelectric conversion layer constituting a photoelectric conversion element). The photoelectric conversion layer is usually formed on a substrate. That is, the photoelectric conversion layer collectively constitutes a substrate and a laminate. Hereinafter, the photoelectric conversion layer and its preparation method will be described in detail.

[Laminated body and its manufacturing method]

The laminate (electrode) of the present invention comprises a substrate and a photoelectric conversion layer (a photoelectric conversion layer formed using the composition) laminated on the substrate.

The substrate may be a conductive substrate, depending on the application. The conductive substrate is usually composed only of a conductor (or a conductor layer), and generally, a substrate on which a conductor layer (or a conductive layer or a conductive film) is formed on a substrate (base substrate) to be a base is used. Also, in this case, the photoelectric conversion layer is formed on the conductor layer.

The conductor (conductive agent) can be appropriately selected depending on the application, and examples thereof include conductive metal oxides (for example, tin oxide, indium oxide, zinc oxide, and lanthanum-doped metal oxides) Tin, etc., tin-doped metal oxide (tin-doped indium oxide, etc.), aluminum-doped metal oxide (doped aluminum-doped zinc oxide, etc.), gallium-doped metal oxide (doped with gallium) An electric conductor such as zinc oxide or the like, a metal oxide doped with fluorine (such as fluorine-doped tin oxide), or the like. These conductors may be used alone or in combination of two or more. Also, the electrical conductors can generally be transparent conductors.

Examples of the base substrate include an inorganic substrate (for example, glass) and an organic substrate [for example, a polyester resin (for example, polyethylene terephthalate or polyethylene naphthalate), and a polycarbonate resin. , a cycloolefin resin, a polypropylene resin, a cellulose resin (such as cellulose triacetate), a polyether resin (such as polyether oxime), a polysulfide resin (such as polyphenylene sulfide), or a poly A substrate or a film (a plastic substrate or a plastic film) formed of a plastic such as a quinone imide resin. In the present invention, since a sintering step of a semiconductor is not required, it is possible to use a plastic substrate (plastic film) as a base substrate.

The photoelectric conversion layer can be formed by applying the composition onto a substrate (conductor layer). The coating method is not particularly limited, and examples thereof include an air knife coating method, a roll coating method, a gravure coating method, a blade coating method, a doctor blade method, a doctor roll method, a dip coating method, a spray method, and a spin coating method. Method, inkjet printing method, etc. After coating, it is dried at a predetermined temperature (for example, from room temperature to about 150 ° C).

Further, as described above, the dye is adhered to the semiconductor containing semiconductor by applying the semiconductor and the ionic polymer to the substrate. And a coating film of an ionic polymer is contained in the photoelectric conversion layer. Examples of the method for adhering the dye include a method of spraying a solution containing a dye onto a coating film, a method of immersing a substrate on which a coating film is formed, and a solution containing a dye. Further, it may be dried in the same manner as described above after spraying or immersion.

Further, in the present invention, after the composition is applied onto the substrate, the semiconductor is not sintered (or calcined) [or is not subjected to heat treatment at a high temperature (for example, 400 ° C or higher)] to form a photoelectric conversion layer. In the present invention, a photoelectric conversion layer having superior photoelectric conversion characteristics can be formed without undergoing the sintering step. Further, although the specific surface area of the semiconductor is reduced by sintering, as described above, in the present invention, since the photoelectric conversion layer can be formed even without sintering, it is possible to maintain the surface area derived from the semiconductor.

In the above manner, a photoelectric conversion layer is formed on a substrate (conductive substrate), and an electrode (layered body) can be obtained. For example, the thickness of the electrode may be from 0.1 to 100 μm (for example, from 0.3 to 70 μm), preferably from 0.5 to 50 μm (for example, from 0.7 to 40 μm), and further preferably from about 1 to 30 μm. Further, for example, the thickness of the photoelectric conversion layer may be from 0.1 to 100 μm (for example, from 0.3 to 70 μm), preferably from 0.5 to 50 μm (for example, from 1 to 30 μm), and further preferably from about 3 to 20 μm.

In the above manner, the obtained laminated system has a conductor layer and a photoelectric conversion layer, and can be utilized as an electrode constituting the photoelectric conversion element. Hereinafter, the photoelectric conversion element will be described in detail.

[Photoelectric Conversion Element]

The photoelectric conversion element includes the laminate (electrode). That is, the photoelectric conversion element (battery) includes the electrode and the counter electrode with respect to the electrode. An example of a representative photoelectric conversion element is a solar battery. In particular, in the case where the photoelectric conversion layer contains a dye, the photoelectric conversion element forms a dye-sensitized solar cell.

For example, a solar cell includes a laminate as an electrode, a counter electrode disposed opposite to the electrode (the photoelectric conversion layer side of the electrode), and an electrolyte layer interposed between the electrodes and sealed. That is, the electrolyte layer (or electrolyte) is interposed (or sealed) by using a sealing material [for example, comprising a thermoplastic resin (ionomer resin, etc.), a thermosetting resin (epoxy resin, a siloxane resin). The sealing material, etc., seals the space or void formed by the two electrodes (or their edges).

Further, the counter electrode is a positive electrode or a negative electrode depending on the type of the semiconductor constituting the electrode (or the laminated body). That is, when the semiconductor is an n-type semiconductor, the positive electrode is formed on the counter electrode (the laminate is the negative electrode); and when the semiconductor is a p-type semiconductor, the negative electrode is formed on the counter electrode (the laminated body is the positive electrode).

Similarly to the laminate, the counter electrode includes a conductive substrate and a catalyst layer (positive catalyst layer or negative catalyst layer) formed on the conductive substrate (or on the conductor layer of the conductive substrate). Further, the conductor layer has a reducing ability in addition to conductivity, and it is not necessary to provide a catalyst layer. Further, the surface of the conductor layer or the catalyst layer is opposed to the laminate (or electrode). In the counter electrode, the conductive substrate may have a substrate having a conductor layer and a catalyst layer (conductive catalyst layer) formed on the base substrate, in addition to the substrate similar to the above. Further, the catalyst layer (positive electrode catalyst layer or negative electrode catalyst layer) is not particularly limited, and can be formed using a conductive metal (gold, platinum, or the like), carbon, or the like.

The catalyst layer may be a non-porous layer (or a non-porous layer) or a layer having a porous structure (porous layer). The electrode is preferably an electrode having a porous layer (in detail, an electrode having a porous layer on the outermost surface). When the electrode including the porous layer and the photoelectric conversion layer are combined, the storage function can be efficiently performed, and the photoelectric conversion element having a large storage capacity can be easily obtained.

In the electrode (counter electrode), the porous layer is usually a layer (porous catalyst layer) which functions as a catalyst layer (positive electrode catalyst layer or negative electrode catalyst layer). The porous catalyst layer may include a porous catalyst component (porous catalyst component), or may include a porous component (porous component) and a catalyst component held by the porous component, or may contain a combination These are the same. In other words, the porous catalyst component is porous and exhibits a function as a catalyst component (a component having both a porous property and a catalytic function). Further, in the latter form, the porous component may have a catalytic function.

Examples of the porous catalyst component include metal fine particles (for example, platinum black), and porous carbon [carbon black (carbon black aggregate) such as activated carbon, graphite, Ketjen black, furnace black, and acetylene black, Carbon nanotubes (carbon nanotube aggregates), etc.]. These components may be used alone or in combination of two or more. Among the porous catalyst components, activated carbon or the like can be suitably used.

Examples of the porous component include metal compound particles (for example, particles (microparticles) of the above-exemplified conductive metal oxide (for example, tin-doped indium oxide), etc.] Wait. These components may be used alone or in combination of two or more. Further, examples of the catalyst component include a conductive metal (for example, gold or platinum).

The shape (or form) of the porous catalyst component and the porous component is not particularly limited, and may be particulate, fibrous or the like, and is preferably particulate.

For example, the particulate porous catalyst component and the porous component (porous particle) may have an average particle diameter of 1 to 1000 μm (for example, 5 to 700 μm), preferably 10 to 500 μm (for example, 20 to 400 μm). Further preferably, it may be 30 to 300 μm (for example, 40 to 200 μm), and particularly preferably 50 to 150 μm (for example, 70 to 100 μm).

For example, the porous catalyst component and the porous component may have a specific surface area of 1 to 4000 m ² /g (for example, 10 to 3500 m ² /g), preferably 20 to 3000 m ² /g (for example, 30 to 2500 m ^{2 )} Further, it is preferably 50 to 2000 m ² /g (for example, 100 to 1500 m ² /g), and particularly preferably 200 to 1000 m ² /g (for example, 300 to 500 m ² /g).

Further, the porous layer (porous catalyst layer) may further contain an adhesive component (for example, a resin component such as a thermoplastic resin such as a cellulose derivative (methylcellulose); or a heat of an epoxy resin or the like. Curable resin]}.

The proportion of the adhesive component may be, for example, 0.1 to 50% by weight, preferably 0.5 to 40% by weight, and further preferably 1 to 30% by weight, based on the entire porous layer (porous catalyst layer). (for example, 3 to 20% by weight).

The electrode having the porous layer may have at least a porous layer, and usually includes at least a substrate (which may also be a substrate of a conductive substrate). With a porous catalyst layer. Examples of the electrode of the representative porous layer include: (i) an electrode (or a laminate) comprising a conductive substrate (a substrate on which a conductor layer is formed on a base substrate, a conductive substrate as exemplified), a porous catalyst layer composed of a porous catalyst component formed on the conductive substrate (or a conductor layer); (ii) an electrode (or laminate) comprising a base substrate (the base substrate described above) And a porous catalyst layer formed of a porous component and a catalyst component (for example, a porous component carrying a catalyst component) formed on the base substrate.

For example, the porous layer (porous catalyst layer) may have a thickness of 0.1 to 100 μm (for example, 0.3 to 70 μm), preferably 0.5 to 50 μm (for example, 0.7 to 40 μm), and further preferably 1 to 30 μm. about.

The electrolyte layer may be formed using an electrolyte containing an electrolyte and a solvent, or may be formed using a solid layer (or gel) containing an electrolyte. The electrolyte constituting the electrolytic solution is not particularly limited, and examples thereof include a general-purpose electrolyte such as a combination of a halogen (halogen molecule) and a halide salt [for example, a combination of a bromine and a bromide salt, and a combination of an iodine and an iodide salt. and many more. Examples of the relative ions (cations) constituting the halide salt include metal ions [for example, alkali metal ions (for example, lithium ions, sodium ions, potassium ions, cesium ions, etc.), alkaline earth metal ions (for example, magnesium ions, calcium ions). Etc., etc.], a fourth-order ammonium ion [tetraalkylammonium salt, pyridinium salt, imidazolium salt (for example, 1,2-dimethyl-3-propylimidazolium salt), etc.]. The electrolyte may be used alone or in combination of two or more.

Among these, among the preferable electrolytes, a combination of iodine and an iodide salt, particularly iodine and a metal iodide salt [for example, an alkali metal salt (lithium iodide, sodium iodide, potassium iodide, etc.), A combination of a grade 4 ammonium salt or the like].

The solvent constituting the electrolytic solution is not particularly limited, and a general-purpose solvent can be used, and examples thereof include alcohols (for example, alkanols such as methanol, ethanol, and butanol; ethylene glycol and diethylene glycol; , glycols such as polyethylene glycol), nitriles (acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, benzonitrile, etc.), carbonates (ethylene carbonate, propylene carbonate) , diethyl carbonate, etc.), lactones (γ-butyrolactone, etc.), ethers (1,2-dimethoxyethane, dimethyl ether, diethyl ether, etc.) ; tetrahydrofuran, 2-methyltetrahydrofuran, two 4-methyl two Such as cyclic ethers), cyclobutyl hydrazines (cyclobutyl hydrazine, etc.), fluorenes (dimethyl hydrazines), guanamines (N, N-dimethylformamide, N, N- Dimethylacetamide, etc.), water, and the like. The solvent may be used alone or in combination of two or more.

Further, in the photoelectric conversion element, the ionic polymer is in contact with the electrolytic solution (or the ionic polymer is present in the electrolytic solution), and as described above, the pH of the ionic polymer is adjusted, and the photoelectric conversion element is also used. It is preferred to maintain the pH of the ionic polymer. Specifically, in the case where an anionic polymer is used as the ionic polymer, the pH (25 ° C) of the electrolytic solution (the ionic polymer in the electrolytic solution) can also be selected from the range of 10 or less (for example, 0.1 to 8). For example, it may be less than 7 (for example, 0.15 to 6.5), preferably 6 or less (for example, 0.2 to 5), further preferably 4 or less (for example, 0.3 to 3), and particularly preferably 2 or less ( For example, 0.5 to 1.5), usually 3 or less (for example, 1 to 3).

Further, in the case where the cationic polymer is used as the ionic polymer, the pH (25 ° C) of the electrolytic solution (or the ionic polymer in the electrolytic solution) can be selected from the range of 5 or more (for example, 6 to 10). For example, it may be 7 or more (for example, 7.5 to 14), preferably 8 or more (for example, 8.5 to 14), further preferably 9 or more (for example, 9.5 to 13.5), and particularly preferably 10 or more (for example, 10.5 to 13).

From the viewpoint of pH adjustment, the components constituting the electrolytic solution may be suitably used as components which do not affect the pH adjustment. For example, in the case where the ionic polymer is composed of an anionic polymer, a neutral solvent or a non-base solvent (for example, a non-amine solvent) may be suitably used as the electrolyte. On the other hand, in the case where the cationic polymer is used to constitute the ionic polymer, a neutral solvent or a non-acid solvent (or an aprotic solvent) may be suitably used as the electrolyte.

Further, the concentration of the electrolyte in the electrolyte may be, for example, 0.01 to 10 M, preferably 0.03 to 8 M, and more preferably 0.05 to 5 M. Further, in the case of combining a halogen (iodine or the like) with a halide salt (such as an iodide salt), the ratio may be a halogen/halide salt (mol ratio) of 1/0.5 to 1/100, preferably Further preferably, from 1/1 to 1/50, it may be from about 1/2 to 1/30.

In addition, examples of the electrolyte constituting the solid layer containing the electrolyte include a solid electrolyte (for example, a resin component [for example, a thiophene-based polymer (for example, polythiophene) or the like) and an oxazole system. a polymer (for example, poly(N-vinylcarbazole) or the like), an organic solid component such as a low molecular organic component (for example, naphthalene, anthraquinone, anthraquinone, etc.), an inorganic solid component such as silver iodide, etc. . These components may be used alone or in combination of two or more.

Further, the solid layer may hold the electrolyte or the electrolytic solution on the gel substrate [for example, a thermoplastic resin (polyethylene glycol, polymethyl methacrylate, etc.), a thermosetting resin (epoxy resin, etc.), etc. The solid layer.

Example

Hereinafter, the present invention will be described in more detail based on the examples, but the present invention is not limited by the examples.

(Example 1)

10 parts by weight of a mixture of titanium oxide particles ("ST-01", average primary particle diameter: 7 nm, specific surface area: 300 m ² /g, anatase crystal), and an anionic polymer-containing dispersion ( "Nafion 117" manufactured by Aldrich Co., Ltd., water and 1-propanol dispersion contained in a ratio of 20%, ion exchange capacity of 0.95 to 1.03 meq/g, pH (25 ° C) = 1, and the area occupied per molecule 0.024 nm ² ) 25 parts by weight (that is, 5 parts by weight of an anionic polymer), a pigment (N719, manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 1188.57, and an occupied area of about 1 nm ² per molecule) 0.1 part by weight and methanol The titanium oxide dispersion was prepared in an amount of 65 parts by weight.

The obtained titanium oxide particle dispersion liquid was applied onto the ITO layer side of an ITO-attached glass substrate (manufactured by Luminescence Technology Co., Ltd., size: 25 mm × 25 mm, thickness of ITO layer: 0.14 μm) by a doctor blade method, and then air, 70 The mixture was dried at ° C to obtain a substrate of a titanium oxide electrode (negative electrode) to which a dye was adsorbed (the thickness of the coating film after drying was 5 μm).

The ITO layer side (dye adsorption side) of the titanium oxide electrode to which the dye was adsorbed and the counter electrode having the porous layer were formed at intervals of 50 μm. [The electrode includes a glass substrate with ITO (manufactured by Luminescence Technology Co., Ltd., size 25 mm ×) 25 mm, thickness of ITO layer 0.14 μm), and activated carbon powder by using a doctor blade method (Tokyo A slurry (10% by weight of an aqueous dispersion containing methylcellulose (manufactured by Tokyo Chemical Industry Co., Ltd.) in an amount of 0.1 part by weight based on 1 part by weight of the activated carbon powder) was applied to the ITO. The ITO layer side (on the side of the activated carbon catalyst layer) on the layer is opposed to each other, and the sealing material or the spacer is used to bond the periphery of each substrate (or each electrode or each ITO layer side) (manufactured by Mitsui DuPont Polychemical Co., Ltd. "Himilan" is sealed, and a dye-sensitized solar cell is produced by filling an electrolyte solution in a space formed between two substrates (or two electrodes) (or a space sealed by a sealing material). Further, in the electrolytic solution, an acetonitrile solution containing 0.5 M of lithium iodide and 0.05 M of iodine was used.

Then, the obtained dye-sensitized solar cell was evaluated under the conditions of AM 1.5, 100 mW/cm ² , and 25 ° C using a sunlight simulator ("XES-301S+EL-100" manufactured by Sanyo Electric Co., Ltd.).

(Example 2)

A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 1 except that the electrode having the porous layer was used. The electrode was made of a glass substrate with ITO and contained therein. a slurry of ITO powder (manufactured by Aldrich Co., Ltd., having a particle diameter of <50 nm and a specific surface area of 27 m ² /g) (containing 0.1 part by weight of methyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd.) in an amount of 1 part by weight of the ITO powder) The 10% by weight aqueous dispersion was applied onto a substrate of a porous layer (thickness: 5 μm) formed on the ITO layer, and an electrode coated with platinum at a thickness of 3.5 nm in accordance with a sputtering method was further used.

(Example 3)

A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 1 except that the electrode having the porous layer was used. The electrode was made of a glass substrate with ITO and contained therein. A slurry of platinum-coated carbon powder (made by Shifu Metal Industrial Co., Ltd., IFPC40-1I) (containing 1 part by weight of platinum-loaded carbon powder, containing methyl cellulose (Tokyo Chemical Industry Co., Ltd.) 0.1 part by weight of a 10% by weight aqueous dispersion) an electrode coated on a substrate of a porous layer (thickness 5 μm) formed on the ITO layer.

(Example 4)

In the first embodiment, a dye-sensitized solar cell was produced and evaluated in the same manner as in Example 1 except that the electrode was used as the counter electrode. The electrode was a non-porous structure electrode [with ITO glass] A substrate (manufactured by Luminescence Technology Co., Ltd., size: 25 mm × 25 mm, thickness of the ITO layer: 0.14 μm), and a platinum layer formed on the ITO layer by a sputtering method (platinum layer thickness: 3.5 nm, electrode area: 6.25 cm ² /g) ) of the electrode].

For each of the dye-sensitized solar cells obtained in the examples, the output characteristics are shown in Fig. 1, and the change in the open voltage after the light-shielding is shown in Fig. 2 . Also, the shading is performed by turning off the bulb of the sunlight simulator. As is clear from the figure, in the embodiment, photoelectric conversion characteristics and power storage functions are provided. Among them, in the dye-sensitized solar cell (Examples 1 to 3) in which the electrode having the porous layer was used as the counter electrode, it was found to have a high power storage function.

[Possibility of industrial use]

The composition of the present invention is used to form a photoelectric conversion layer or a photoelectric conversion element. In particular, in the present invention, a photoelectric conversion layer having a storage function can be formed not only by photoelectric conversion characteristics. Further, since the photoelectric conversion layer can be formed without sintering, a photoelectric conversion layer can be formed on a plastic substrate or the like. The photoelectric conversion element obtained by using the composition is suitable as a photovoltaic cell such as a solar cell (particularly, a dye-sensitized solar cell).

Claims (18)

A composition for a photoelectric conversion layer for forming a composition of a photoelectric conversion layer having a storage function, comprising a semiconductor and an ionic polymer, and the ratio of the ionic polymer to 1 part by weight of the semiconductor It is 0.05 to 100 parts by weight, wherein the ionic polymer is a strongly acidic ion exchange resin. The composition of claim 1, wherein the semiconductor is a metal oxide. The composition of claim 1, wherein the combination of the semiconductor and the ionic polymer is (i) a combination of an n-type semiconductor and an ionic polymer comprising an anionic polymer, or (ii) a p-type semiconductor and a cation-containing compound. A combination of ionic polymers of a polymeric polymer. The composition of claim 3, wherein the combination of the semiconductor and the ionic polymer is a combination (i) the n-type semiconductor comprises titanium oxide particles. The composition of claim 3 or 4, wherein the anionic polymer has a sulfonic acid group. The composition of claim 3 or 4, wherein the pH of the aqueous solution or aqueous dispersion of the anionic polymer is less than 7 at 25 °C. The composition of any one of claims 1 to 4, wherein the ratio of the ionic polymer is from 0.1 to 10 parts by weight relative to 1 part by weight of the semiconductor. The composition of any one of claims 1 to 4, wherein the semiconductor comprises titanium oxide nanoparticles, which is an ionic polymer having a pH of 3 or less containing a fluorine-containing resin having a sulfonic acid group, and The ratio of the ionic polymer is from 0.2 to 1 part by weight with respect to 1 part by weight of the semiconductor. The composition of any one of claims 1 to 4, which further contains a pigment. The composition of claim 9, wherein the pigment is a ruthenium complex pigment. A laminate comprising a laminate of a conductive substrate and a photoelectric conversion layer laminated on the substrate, the photoelectric conversion layer being formed of the composition according to any one of claims 1 to 10. The laminate according to claim 11, wherein the conductive substrate is a plastic substrate on which a conductor layer is formed. The laminate of claim 11 or 12, wherein the photoelectric conversion layer has a thickness of 0.1 to 100 μm. A method of producing a laminate according to any one of claims 1 to 10, which is characterized in that the composition according to any one of claims 1 to 10 is applied onto a conductive substrate without causing the semiconductor to be sintered. A photoelectric conversion element comprising the laminate according to any one of claims 11 to 13. The photoelectric conversion element according to claim 15, which comprises a dye-sensitized solar cell having a structure comprising a photoelectric conversion layer containing a pigment as an electrode; and a counter electrode disposed opposite to the electrode; The electrolyte layer is interposed between the electrodes and has been sealed. The photoelectric conversion element of claim 16, wherein the counter electrode contains a porous layer. A method of imparting a storage function to a photoelectric conversion layer, which is contained in a photoelectric conversion layer containing a semiconductor, and contains an ionic polymer in a ratio of 0.05 to 100 parts by weight based on 1 part by weight of the semiconductor.